Coilable tape rule with improved connection between spring and hub

ABSTRACT

A power returnable tape rule has an improved connection between the inner end of the power spring and the hub. The hub has an axially elongated passage therethrough with shoulders at the axial ends thereof which seat in notches formed in the edges of the spring extending therethrough. These shoulders are located intermediate the transverse dimension of the passage and are inclined upwardly towards the axial ends. Bosses on the opposing wall of the passage limit the clearance in the passage and thereby the opportunity for the spring to be lifted from the shoulders.

BACKGROUND OF THE INVENTION

The present invention relates to power returnable coilable rules, andmore particularly, to connections between the coilable power spring anda fixed hub.

Power returnable coilable rules have enjoyed considerable success in themarketplace and are very widely employed. Generally, such rules have apower spring providing the retracting force to draw the metal ruleinwardly of the casing and effect its coiling thereabout. In some suchrules, the spring operates to effect rotation of a reel to which itsouter end is connected, and its inner end is engaged with a fixed hubabout which the reel rotates. In some instances, the projecting end ofthe spring is bend about the hub to secure it thereto.

Since there are substantial forces exerted upon the connection of thespring to the hub, it is desirable that there be a positive engagementtherebetween to locate the spring in a fixed position relative to thehub and essentially to preclude inadvertent disengagement.

It is an object of the present invention to provide an improved powerreturnable coilable metal rule in which there is a novel and secureinterengagement between the inner end of the spring and the hub aboutwhich the reel rotates.

It is also an object to provide such a coilable metal rule in which theelements may be economically fabricated and readily assembled to providesuch secure engagement between the rule and spring and the hub.

Another object is to provide such a coilable rule in which the end ofthe spring is precisely positioned relative to the hub.

Still another object is to provide such a coilable rule in which the huband power spring may be readily assembled by automated procedures.

SUMMARY OF THE INVENTION

It has now been found that the foregoing and related objects may bereadily attained in a power returnable tape rule having a case with anexit aperture in the peripheral wall thereof, an elongated spring coiledtherewithin, an elongated tape rule blade coiled thereabout with itsouter end extending outwardly of the exit aperture and its inner endsecured to the outer end of the coiled elongated spring, and a hub withwhich the inner end of the spring is engaged by an improved connection.The hub has an axially elongated transverse passage therethrough withaxially extending shoulders at each axial end of the passage, and thespring has its inner end portion passing through the passage withopposed notches therein seating the shoulders to engage the spring inthe passage.

Preferably, one of the axially extending walls of the hub defining thepassage has the shoulders formed thereon and the other axially extendingwall has bosses thereon reducing the unobstructed spacing between thewalls.

Desirably, the shoulders are of narrow width relative to, andintermediate the transverse dimension of the passage, and they areinclined upwardly towards the adjacent axial end of the passage. Theportion of the inner end of the spring which extends beyond the hub isbent about the hub.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the two halves of a rule housing inspaced position, with a cartridge containing a spring and hub joined inaccordance with the present invention shown as mounted upon a jig priorto assembly in the housing;

FIG. 2 is an elevational view to an enlarged scale of the cartridge andjig assembly of FIG. 1;

FIG. 3 is a sectional view thereof along the line 3--3 of FIG. 2;

FIG. 4 is a perspective view of the jig seen in FIGS. 1-3;

FIG. 5 is a fragmentary plan view of the inner end of the spring;

FIG. 6 is a perspective view of the hub shown in FIGS. 1-3 with the endof the fragmentarily illustrated spring shown prior to insertionthereinto;

FIG. 7 is a fragmentary sectional view of the hub;

FIG. 8 is a fragmentary plan view of the inner end of the rule blade;

FIG. 9 is a fragmentary plan view of the outer end of the spring;

FIG. 10 is a fragmentary view of the spring and rule blade as engaged;

FIG. 11 is a fragmentary perspective view of the hub and spring asinitially assembled with a portion of the hub broken away;

FIG. 12 is a fragmentary plan view of the inner end of a rule bladeemploying an alternate embodiment of lock configuration;

FIG. 13 is a fragmentary plan view of the outer end of the spring forthe alternate embodiment; and

FIG. 14 is a fragmentary perspective view of the rule blade and springas engaged and utilizing the alternate embodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Turning first to FIG. 1 of the attached drawings, therein illustrated isa partially assembled power returnable tape rule embodying the presentinvention. The case for the rule is comprised of two mating sectionsgenerally designated by the numerals 10, 12 and in which is to be seatedthe cartridge generally designated by the numeral 14. The cartridge 14includes a coilable metal rule blade generally designated by the numeral16 extending outwardly therefrom, and the cartridge 14 is seated on theassembly jig generally designated by the numeral 18 with the hook 20 atthe outer end of the blade 16 hooked over a surface on the jig 18. Thecartridge 14 includes the reel or spool 24 and the hub generallydesignated by the numeral 22 about which the spring (not shown) iscoiled and about which the reel 24 is rotatable.

The case or housing sections 10, 12 each have an end wall 28 and aperipheral wall 26 extending thereabout with an exit aperture 30adjacent the base portion thereof. Also provided in the end wall 26above the exit aperture 30 in the section 10 is a notch 32, and thesection 12 has a cooperating notch 31 and recessed surface 33. Whenjoined, the notches 31, 32 in the sections 10, 12 together provide achannel in which is slidable the lock button 34 of the lock assemblygenerally designated by the numeral 36. At spaced points about the casesections 10, 12 are provided aligned bosses 38, and the bosses 38 of thesection 10 have projecting pins 40 which seat in mating recesses 42 ofthe section 12 for engagement to retain the casing halves in alignment.Threaded fasteners (not shown) seat in countersunk apertures in thesection 12 and threadably engage in the pins 40 of the section 10 tolock the sections 10, 12 together.

The side wall 28 of each of the case sections 10, 12 has a centrallydisposed boss 44 which is cooperatively configured to seat in aperturesat the axial ends of the hub 22 to prevent the rotation thereof. Alsoseen in FIG. 1 is the speed control insert 46 which is secured in theexit aperture 30 and through which the blade 16 extends.

As is well known, the lock assembly 36 is movable downwardly against theblade 16 within the casing to lock the blade 16 in an extended position.Upon release of the blade 16, it retracts into the casing until the hook20 at the outer end of the blade 16 abuts the walls of the speed controlinsert 46 about the exit aperture 30 to limit its movement inwardly ofthe casing.

As seen in FIGS. 1-4, the jig 18 includes a base 48 and an upstandingleg 50 which has a rectangular boss 52 on the inner surface of its upperend which seats in the hub 22. A projecting arm 54 adjacent the lowerend of the leg 50 extends above the base 48. The extended blade 16passes about the arm 54 to orient the outer end portion of the blade 16in a substantially straight path so that the hook 20 will seat againstthe base 48 in a stable position. As will be pointed out more fullyhereinafter, the jig 18 is utilized to mount the cartridge 14 in thecasing section 10.

As seen in FIG. 3, the reel 24 is provided by a pair of mating sections56, 58 each having a base wall 60 and opposed circular walls 62 spacedinwardly from the margins thereof which abut and define a spring chamber64 therewithin and a peripheral channel 66 in which the blade 16 iscoiled.

The outer surfaces of the base walls 60 have a central boss 68 and anannular boss 70 spaced outwardly therefrom which provide bearingsurfaces in the casing, and bores 72 extend through the bosses 68 andwalls 60. Rotatably seated in the bores 72 of the sections 56, 58 arethe ends of the hub 22.

As seen in FIGS. 6 and 7, the hub 22 of the present invention has agenerally cylindrical body portion 74 and enlarged end portions 76providing rectangular recesses 78 in their outer surfaces. As previouslyindicated, these recesses 78 are cooperatively configured to seat therectangular bosses 44 on the side walls 28 of the casing sections 10, 12and prevent its rotation with respect thereto.

The axially extending body portion 74 of the hub 22 has an axiallyelongated passage 80 therethrough and one of the elongated wallsdefining the passage is provided with depending bosses 82 spaced alongits length. The other of the elongated walls has, at its two ends andgenerally centrally of the passage 80, a pair of shoulders 84 which areupwardly inclined towards the ends of the passage 80.

As seen in FIG. 3, the coiled power spring generally designated by thenumeral 86 has its inner end portion 88 extending through the passage 80in the hub 22, and the passage 80 is dimensioned with an axial lengthonly slightly larger than the width of the end portion 88. The endportion 88 has a pair of opposed notches or slots 90 which receive theshoulders 84 in the hub passage 80 to accurately position the inner endportion and lock it within the passage 80. The projecting end portion 88of the spring 86 is bent about the outer surface of the body portion 74as seen in FIG. 11, and it is of a length which will terminate prior tothe other end of the passage 80. Thus, the spring is preciselypositioned and its projecting length is fixed by the positioning of thenotches 91. The spring 86 is coiled about the hub 22, and its outer endportion 92 extends through a slot (not shown) in the circular walls 62of the cartridge 24 and is engaged with the blade 16 as will be morefully described hereafter.

As seen in FIG. 9, the outer end portion 92 of the spring 86 has anelongated tongue 94 of reduced width with an enlarged portion 96intermediate its length providing a narrow width section 98 at the outerend and a narrow width section 100 inwardly of the enlarged portion 96.The leading and trailing edges of the enlarged portion 96 are oppositelyinclined inwardly and provide shoulders 97.

As seen in FIG. 8, the inner end portion 102 of the blade 16 has anelongated aperture 104 therein with an enlarged width portionintermediate its length providing corner tabs 106 with inwardly inclinedopposed surfaces 108.

As seen in FIG. 10, in assembling the spring 86 and blade 16, the tongue94 is placed upon the upper surface of the blade 16 with the enlargedportion 96 overlying the aperture 104. The enlarged portion 96 is pusheddownwardly through the aperture 104 and the portions adjacent theshoulders 97 seat under the corner tabs 106 while the sections 98 and100 extend along the upper surface of the blade 16. It will beappreciated that the inclined surfaces on the tabs 106 and shoulders 97provide cam surfaces which facilitate the displacement of the enlargedportion 96 through the blade 16.

As will be appreciated, the shoulders 97 abut the wall of the blade 16defining the ends of the aperture 104 upon relative longitudinalmovement in either direction to prevent inadvertent disengagement duringnormal use.

Turning now to FIGS. 12-14, another embodiment of locking elements isillustrated. The outer end portion 92a of the spring 86 has an elongatedtongue 94a with an elongated section 110 of reduced width and anenlarged tip 112 with an arcuate leading edge 114 and generallyrectilinear trailing edges 116 providing shoulders. An arcuatelytapering section 118 at the inner end of the tongue 94a providesoppositelY disposed shoulders 120. The inner end portion 102a of theblade 16 has an elongated aperture 104a with a reduced width portionintermediate its length providing opposed fingers 122.

To assemble this lock as shown in FIG. 14, the narrow portion of thetongue 94a is placed over the aperture 104a, and the tongue 94a ispressed downwardly to flex the fingers 122 downwardly sufficiently topermit the elongated section of the tongue 94a to pass thereby. Thefingers 122 then seat thereover to trap the tongue 94a in the aperture104a. If the spring 86 is moved rearwardly, the shoulders 116 on thetrailing edge of the tip will abut the leading edges of the fingers 122to limit further relative movement. If the spring 86 is moved forwardlythe shoulders 120 will abut the trailing edges of the fingers 122 tolimit further movement.

As illustrated, the blade 16 desirably has a concavo-convex transverseconfiguration to increase its stiffness and enable it to stand out fromthe casing for an extended distance. As the blade 16 is retracted intothe casing, the blade is flattened as it enters the casing. The spring86 is generally of flat transverse configuration as illustrated.

To assemble the rule, the hub is seated in one reel section and theinner end of the spring is inserted into the hub. As it is pressedthereinto, the tapered shoulders flex the edge portions of the springupwardly to allow them to pass over the shoulders until the notchesregister therewith, at which time the edge portions are sprungdownwardly thereover. This locks the spring on the shoulders in thepassage, after which the projecting end portion is bent as seen in FIG.11. The shoulders and notches ensure proper position of the springrelative to the hub as well as effect locking engagement therebetween.The spring may then be coiled in the spring chamber and the other reelsection assembled to secure the spring and hub by sonically oradhesively bonding the reel sections.

The projecting outer end of the spring is locked into the inner end ofthe blade which is then coiled about the reel. The cartridge is thenseated on the jig with the blade extended to lock the hook over the endof the base as seen in FIGS. 1 and 2, and the case section is rotated90° and brought thereagainst to seat the hub in its boss and to positionthe tape hook outwardly of the exit aperture. The jig may then beremoved, and the other section of the casing assembled over thecartridge. Each of these operations may be effected on automatedequipment to reduce the time and cost of assembly.

In use, the blade is pulled outwardly from the case and the springtension is increased as this occurs. When the blade is released, thepower spring produces rotation of the reel and the coiling of the bladethereon. Even if the spring is loosely coiled about the hub, its innerend is securely engaged with the hub by the seating of the shoulders inthe notches.

As is conventional, the spool and hub are molded from synthetic resin,conveniently by injection molding. The resins from which such parts aremolded include acrylonitrile/butadiene/styrene interpolymer (ABS),polyamides such as nylon, rubber modified polystyrene (HIPS),styrene/acrylonitrile copolymer (SAN), polypropylene, and the like.

The housing may also be molded from such resins or it may be cast orforged from metal such as aluminum, steel, zinc and brass. The tape andspring will generally comprise tempered steel strip.

Thus, it can be seen that the power returnable tape rules of the presentinvention may be fabricated from durable components and assembledreadily to provide a long lived structure in which the spring and thehub are securely locked in assembly.

Having thus described the invention what is claimed is:
 1. In a powerreturnable tape rule having a case with an exit aperture in theperipheral wall thereof, an elongated spring coiled therewith, andelongated tape rule blade coiled therewithin with its outer endextending outwardly of said exit aperture and its inner end secured tothe outer end of the coiled elongated spring, and a hub with which theinner end of said spring is engaged, the improvement comprising anaxially elongated transverse passage in said hub, said hub havingaxially extending shoulders at each axial end of said passage, and saidspring having its inner end portion passing through said passage andopposed notches extending inwardly from its side margins seating saidshoulders to engage said spring in said passage, said hub passage beingconfigured and dimensioned to cooperate with said shoulders to limitmovement of said spring when seated on said shoulders.
 2. The powerreturnable coilable tape rule in accordance with claim 1 wherein one ofthe axially extending walls of said hub defining said passage has saidshoulders formed thereon and the other axially extending wall has bossesthereon reducing the unobstructed spacing between said walls.
 3. Thepower returnable coilable tape rule in accordance with claim 1 whereinsaid shoulders are of narrow width relative to the transverse dimensionof said passage and are inclined upwardly towards the adjacent axial endof said passage.
 4. The power returnable coilable tape rule inaccordance with claim 3 wherein said shoulders are intermediate thetransverse dimension of said passage.
 5. The power returnable coilabletape rule in accordance with claim 4 wherein one of the axiallyextending walls of said hub defining said passage has said shouldersformed thereon and the other axially extending wall has bosses thereonreducing the unobstructed spacing between said walls.
 6. The powerreturnable coilable tape rule in accordance with claim 5 wherein theportion of said inner end of said spring which extends beyond said hubis bent about said hub.
 7. The power returnable coilable tape rule inaccordance with claim 1 wherein the portion of said inner end of saidspring which extends beyond said hub is bent about said hub.